Re: Gross Beta Drinking Water Standard Requirements

["Dale Thomas" <Dale.Thomas@guardian.brooks.af.mil>]

     With a gross alpha >15 pCi/L, I would expect the presence of uranium, 
     (and/or thorium), and the descending daughters.  Each of the uranium 
     and thorium decay chains produce several beta emitting daughters that 
     could explain the elevated gross beta if the sample has a high 
     concentration of suspended particles.  Similarly, Ra-226 has several 
     beta emmitters in its descendents.  Note* Ra-226 can be present even 
     in the absence of significant uranium activity.
     
     
     Further evaluation of the sample for uranium, Ra-226, and Ra-228 (if 
     the Ra-226 > 5 pCi/L) may give you and inidication if the 
     gross beta > 50 pCi/L could be explained from the natrually occuring 
     daughters of these chains.
     
     You may also want to instruct the lab to do Sr-89/Sr-90 if you are 
     reasonably close to a reactor that may occasionally release activity 
     to the environment.  Also, evaluation via gamma spectroscopy may be 
     the easiest way to identify the cause of the elevated gross beta.  
     
     Bottom line: Check with the local state regulatory agency and see what 
     the state requirements are.  I suspect that they'll ask you to analyze 
     for Sr-89/Sr-90.
     
     
     
     Dale Thomas
     Health Physicist
     Bioenvironmental Engineering Division
     Occupational and Environmental Health Directorate 
     Armstrong Laboratory
     Brooks AFB, TX 78235
     (210) 536-5816
     email: Dale.Thomas@guardian.brooks.af.mil


______________________________ Reply Separator 
_________________________________ Subject: Gross 
Beta Drinking Water Standard Requirements
Author:  radsafe@romulus.ehs.uiuc.edu at guardian 
Date:    10/16/95 11:42 AM
     
     
  If a site with groundwater samples sent for gross alpha and beta analysis 
  as in accordance with 40 CFR 141 had > 15 pCi/l for alpha > 50 pCi/l for 
  beta measurments, the regulations are clear as to what is required for 
  further anaysis for the exceedences of gross alpha, but it is not clear to 
  me on the requirements for further analysis for the gross beta
  exceedences.  Background was determined for the area and the results were < 
  5 pCi/l and < 50 pCi/l for alpha and beta respectively.  We are also 
  collecting new samples, filtered and unfiltered to see if there was any 
  turbidity effect.
     
  Question:  What radionuclides and what analysis do I analyze for to explain 
  the high gross beta measurements?
     
Meg MacLeod
  meg_macleod@abbsmtp.abb.com